Hi
I am trying to write a new tool. For my purpose i need to track function
entry/exit, I read tracking-fn-entry-exit.txt and see some code of callgrind
(it's not easy to isolate the code that i need), but I am not so good and so
I have some problem.
I write some code that basically insert a call to an helper function at the
beginning of each BB (guest_chase_thresh = 0). Then I simulate a stack
during the execution of the program based on SP changes:
- if VG_(get_fnname_if_entry) is true, I simulate a call
- if the stack pointer provided by Valgrind is bigger than the SP on my
stack, I simulate one or more return (callgrind, I think, call this
operation unwind_call_stack)
This does not work correctly (I compare my result with callgrind), something
is missing. The code fo the simulated stack is attached to this email.
Do you have any suggestion? How can I correcly trace function entry/exit
without analyse all jumps?
Sorry for my bad english.
Emilio.
typedef struct act {
UWord sp;
UWord target;
Char * fn;
} act;
static UWord stack_depth = 0;
static act * current = NULL;
static act * tstack = NULL;
typedef enum jump_t { BB_INIT, CALL, RET, BBCALL, BBRET, BOR, BBBOR } jump_t;
static void print_stack(void) {
UWord depth = stack_depth;
act * c = current;
while(stack_depth > 0) {
VG_(printf)("[%lu] %s()\n", depth, c->fn);
c--;
depth--;
}
}
static void function_enter(UWord target, char * name) {
VG_(printf)("[%lu] Entered %s()\n", stack_depth, name);
}
static void function_exit(UWord target, char * name) {
VG_(printf)("[%lu] Exit %s()\n", stack_depth, name);
}
static void init_stack(UWord csp, UWord target) {
tstack = VG_(calloc)("thread_data", sizeof(act) * 4096, 1);
current = tstack;
/* Function name buffer */
Char * fn = VG_(calloc)("fn name", 256, 1);
/* valgrind call the init function "(below main)" */
VG_(sprintf)(fn, "(below main)");
current->fn = fn;
current->sp = csp;
current->target = 0; /* Fake target */
/* Safety check: we never execute the first
* instruction of this function */
if (VG_(get_fnname_if_entry)(target, fn, 256)) failure("Wrong");
}
static VG_REGPARM(2) void call(UWord target, UWord type_op) {
/* Obtain current stack pointer */
UWord csp = (UWord) VG_(get_SP)(1);
/* Init stack */
if (tstack == NULL) {
init_stack(csp, target);
return;
}
/* Function name buffer */
Char * fn = VG_(calloc)("fn name", 256, 1);
/* Are we entering a new function? */
Bool call_fn = VG_(get_fnname_if_entry)(target, fn, VG_(strlen)(fn));
/* If not, ask valgrind where we are... */
Bool act_fn = True;
if (!call_fn)
act_fn = VG_(get_fnname)(target, fn, VG_(strlen)(fn));
if (!act_fn) {
/*
* Why is this happening?
* I don't know!
*/
VG_(printf)("Valgrind does not know where we are: %p\n", target);
}
if (call_fn) {
/* Before the call, some functions are returned? */
while(current->sp < csp && stack_depth > 0) {
VG_(printf)("We miss a return :(\n");
/* This function is returned */
function_exit(current->target, current->fn);
/* Adjust stack */
stack_depth--;
current--;
}
/* Register the new activation of a function */
stack_depth++;
current++;
current->sp = csp;
current->target = target;
current->fn = fn;
function_enter(current->target, current->fn);
} else if (csp > current->sp) {
/* One or more function returned */
while(stack_depth > 0) {
function_exit(current->target, current->fn);
stack_depth--;
current--;
if (csp <= current->sp) {
VG_(printf)("[%lu] Inside %s\n", stack_depth, current->fn);
/* Safety check */
if (act_fn && VG_(strcmp)(current->fn,fn) != 0) {
VG_(printf)("Simulated stack says you are in %s but valgrind says %s\n", current->fn, fn);
failure("Mismatch during return\n");
}
break;
}
}
}
}
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